Inside Macintosh: Mac OS Runtime Architectures /

Chapter 7 - Fat Binary Programs

A fat binary program (often simply called a fat program) is an program that contains executable code for more than one runtime architecture. Typically you create fat programs when you want compatibility between hardware platforms. For example, a fat application with PowerPC code and CFM-68K code can be executed on both PowerPC-based and 68K-based Macintosh computers. A user can store a fat application on a portable hard drive and then move it between a 68K-based computer and a PowerPC- based computer.

In addition, fat programs designed to patch code or resources can improve performance by reducing the work of the Mixed Mode Manager. Since a fat program can contain both CFM-based code and classic 68K code, it can execute whichever code is necessary to avoid a mode switch.

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Chapter Contents

Creating Fat Binary Programs

Accelerated and Fat Resources